Protective system



Feb. 16 1926. 1,573,622

1 J. BiERMANN@ ET AL.

PROTECTIVE SYSTEM Filed GGt. l7, 1924 3 Sheets-Shei l /2 AAAAAA/ AIAAAAV VY Feb. 16 1926.

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PROTECTIVE SYSTEM Filed Oct. 17, 1924 5 Sheets-Sheet 2 /2 AAI/AAH (vvvvvMAMA nverwLor-S B Otto Ma. Y',

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J. BIERMANNS ET AL Feb. 16 1926.

PROTECTIVE SYSTEM Filed Oct. 17 1924 3 Sheets-Sheet :5

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A AAAAAAA Patented Fels. 16, i926.

UNlTED STATES sPArEN'r ortica.

JOSEF BIERIANNS .AND OTTO MAYR, OF KARLSHORST, GERMANY. ASSIGNORS T0GENERAL ELECTRIC COBIEANY, A. CORFORATION OF NEW YORK.

PROTECTIVE SYSTEM.

' Appiieanon ined october 17, i924.

To all whom 77mg/ concern:

Be it known that We, Josnr lrniiMANNs and Q'r'ro lii'iAYR, citizens ofGermany, residing at Karlslicrst, Germany, have invented certain neivand useful improvements in Protective Systems, ot which the 'followingis a specication.

Our invention relates to improvements in protective systems foralternating` electric current circuits, and more particularly toimprovements in protective systems involving the use of relays in whichcurrent and potential windings cooperate to provide a discriminatingaction dependenton the 'disVv tance between the point o't 'fault and therelay location or on the direction ot the flow oit power at the relaylocation and an object ot .our invention is to provide a protectivesystem having` improved operating characteristics.

ln protective systems involving the use ot relays which havecooperatingcurrent and potential windings and which are to function inconformance With over-current and under-voltage with a time actiondependent substantially Idirectly on the potential and 'inversely on thecurrent, it is essential to the desired discriminating action that thepotential used be that most affected oy the faulty condition. Inprotective systems involvi-na` directional relays which havecooperatinp; current and potential windings and which to function incontori'nance with. the direction et poiver, il is essential to titedesired operation that the potential used 'ne that least affected by thefaulty conditicn.

It is, therefore, an olii ect ot our invention to provide an improvedprotective system vvlierein relays Whose discriminating action isdependent on current and potential can lie energized selectively inaccordance ivitli the potential best adapted to insure the dey sireddiscriminating;` action. lnasmucli as relays involving, cooperatingcurrent ano. potential Win-dings for the functions set i'iorth arerelatively7 expensive in comparison with simple over-current orunder-voltage relays, it is also an object ot our invention to providean improved protective system for a polyphase circuit wherein the numberof relays having' cooperating current and po- L ndings is substantiallyreduced.

Our invention will be better understooo Serial No. '744,197'.

trom the following description taken in connection with theaccoinpanynrs;- drawings and its scope ivill he pointed out in the ap-4clusive, are vector diagrams explanatory ot the embodiment of ourinvention slioivn in Fig'. G, and Figs. l0 and ll illustrate diaerammatically modications of our invention.

Referring' now to Figs. l and G, a polyphase circuit comprisingconductors l, 2 and 3 is arranged to he controlled by suitable circuitinterrupting` means, sucli as a circuit breaker 4; which is .shown asthe latclied closed type and is arranged to loe controlled tor opening'by a trip coil 5 connected in a control circuit 6. For controlline` thecontrol circuit 6 in response to alinormal conditions on the circuit l,2, 3. there is provided an electro-responsive device,

ich as relav 7 comprising' relatively movable cooperating' contacts 8and 9 and cov` operating current and potential winding-s l() and llrespectively tor controlling;i the n'iovenient ot the contacts. Thecurrent Winding' l() is slioivn connected in series re lation with thecircuit l, i., through cur rent transformers l2 and i3 so to beenergized in accordance with the dille/rence between the currents intivo ot the conductors such l and 2. The potential winding ll maynormally he deeiiergjized and tor selectively connectingl the potentialwinding` 1l tor energization in accordance with the potential ot anyphase ot the circuit l, 2, 3 dependent upon the phase at fault,electroresponsive means, such as over-current relays le and l5 arranfredto he energized respectively in acccrdance with the currents in the tivoconductors l. and 2 are provided. For example, the Winding; ot relay 14is connected in circuit ivith the secondary Winding ot the current.transformer l2 so as to he energized in accordance with the curren inthe conductor l and the Windingl oi' relay l5 is connected in circuitwith the secondary alected by the fault.

winding of the current transformer 13 so as to be energized inaccordance with the current in the conductor 2. The relays ltand 15 arearranged to control contacts 1.6 and 17, and 1S and 19 respectively inthe circuits of the secondary windings or' potential transformers 2O and21 so that upon the occurrence ot a fault the potential winding 11 ofrelay 7 will be energized by the desired potential.

Referring now more in particular to Fig. 1, the relay 7 may be of thetype which functions under abnormal circuit conditions with a timeaction dependent substantially .directly on .the potential andinverselyon the current so that the relay nearest the fault will operatethe quickest. lVith relays of this type, examples ot'which are wellknown to the art, it isv essential to the desired discrim'nating actionthat the potential winding 11 vbe energized upon thel occurrence of afault by the potential most lith the arrangement shown in Fig. 1 it willbe clear from the vector diagrams of Figs. 2 to 5, inclusive, thatforany phase fault on the circuit 1, 2, 3 the potential coll 11 ot relay7 is connected to be energized by the potential most affected.

Assuming, for example, a fault between all phases, shown Vectorially inFig. 2, both of the relays 14 and 15 will be energized thus closingcontacts 16 and 18, respectively. This connects the potential winding 11for energization in accordance with the potential ot phase 1, 2, thispotential being substantially in phase with the diiference between thecurrents z', and 2 in the conductors 1 and 2. Assuming a. fault betweenconductors 1 and 2, shown vectorially in Fig. 3, bothof the relays 14and 15 will be energized thus closing contacts 1G and 18, respectively,and connectng the potential winding 11 for energization in accordancewiththe potential et phase 1, 2, this being the potential most aitected.In this case, the difference between the currents l and i, is equal totheir aritlnnetical sum since they are displaced 180O in phaserelatonship. Assuming a fault between 'conductors 2 and 3, shownvectoriallyl in Fig. L1, only relay 15 will be energized. This willclose contacts 18, thereby connecting the potential winding 11 torenergization in accordance with the potential ot phase 2, 3, this bengthe potential most. affected. Assuming a fault between conductors 1 and3, shown vectorially in Fig. 5, only relay 1st will be energized. Thiswill close contacts 16, thereby ccnnecting the potential winding 11 forenergization in accordance with the potential ditl'ercnce between thefaulty conductors 1 and 3, this being the potential most affected by thefault. In the last two cases, there is no iault current in the conductornot at fault, that is to say, 1 and respectively and consequently thefault current Howing in the current winding 1() et relay 7 is equal tothat flowing in conductors 2 or 1 respectively. Tn each case, however,the potential wnding 11 is connected to be 'energized by the potentialdifference between the two faulty conductors and in phase with thecurrent in the current winding 10.

Referring now more in particular to Fig. G, the relay 7 may be ot thetype which functions in conformance wlth the direction et power on thefircuit 1, 2, 3. Vith relays'ot' this type, examples o1 which are wellknown to the art, it is essential in order to insure the requisiteoperating torce for the relay that the potential winding 11 be connectedto the potential least all'ected upon the occurrencey of a fault'causing a change in the direction of power flow. With the arrangementshown in., Fig. G, it will be clear ,from the vector diagrams of Figs. 7to 9, inclusive, that tor any phase fault on the circuit 1, 2, 3, thepotential winding 11 ot relay 7 is connected to be energized by thepotential least affected.

Assuming now a phase fault between conductors 1 and 2, shown vectoriallyin Fig. 7 ,both relays 1-/1 and 15 will be energized thus closingcontacts 1G and 18 respectively. This connects the potential winding 11ot' relay 7 for energization in accordance with the potential of phase1, 3 which is substantially 120 out of phase with the difference betweenthe currents in conductors 1 and 2. Since conductor 3 is not at fault,the potential ot phase 1, is that least a1- fected. Assuming a phasefault between conductors 2 and 3, shown vectorially in Fig. 8, onlyrelay 15 will be energized. This will close contacts 18, therebyconnecting the potential winding 11 for energization in accordance withthe potential ot phase 1, 2. Smilarly, for a phase fault betweenconductors 1 and V3, shown vectorially in Fig. 9, only relay 14; will beenergized. This will close contacts 16, thereby connecting the potentialwinding 11 for energization in accordance with the potential oi' phase2, 3. Thus, in each case, the potential winding 11 is connected to beenergized by the potential between a conductor at fault and one not atfault so that there is a substantial potential diiference on the winding11 to produce a strong operating effect in conjunction with thecooperating current winding 10.

Figs. 10 and 11 illustrate n'iodil'ications ot the embodiments ot ourinvention shown in Figs. 1 and G respectively. In these modifications,the electroresponsive means employed selectively to effect theenergization of the potential winding 11 ot the relay 7 areunder-voltage relays 22 and 23 respcctively. ln Figs. l0 and ll, thepotential connections are made direct without the medium et potentialtransformers and the circuit breaker and control circuit are alsooniitted for the sake ot clearness.

The relays and .923 are arranged to control relatively movablecooperating contacts` 24A, 25, 2G, El and 2S through circuit controllingmembers and 3() arranged 'tor movement 3y the arn'iatures ot the relays.The contacts 2e, 2 and 2S are stationary and the contacts and 27 aremovable and are arranged to be biased toward the ste.- tionary contact2t) by suitable means each as springs and 32 respectively. llach ot themovable contacts 25 and 27 also arranged to be controlled by each ot'the contact controlling members 2S) and 3G.

Referring now to Fig. l0, the relay T oiC the type having adiscriminating time action dependent on the current and potential as'described in connection with the embodiment of our invention shown inFig. l. Under normal conditions of current and potential both orp thecontact controlling members 29 and 30 will be in the position shown. lnthis case, the potential windingl ll is connected across conductors land 2. It, now, there is a fault between these conductors, neither otthe relays Q2 and 23 will drop out since they are energized by thepotentials across phases 2, 3 and 1, 8 respectively. Therefore, thepotential winding ll remains energized by the potential ot phase l, 2,that is, the phase at fault. Assuming a .tault between conductors 2 and3, then the potential across these conductors will tall sutticiently topermit relay 22 to drop out. Consequently, the contact controllingmember 29 will no longer be restrained in the position shown and thecontact 27 will be 'tree to move under the bias of the spring to engagethe contact 26, thereby Connecting 'the potential winding ll across thefaulty conductors 2 and 3. Similarly, 'for a fault between conductors land 3, the potential winding will be connected across these conductors.Thus, in every case the potential winding 'll is connected to thepotential most affected by the fault.

Referring now to Fig. ll, the relay 7 is ot the power directional typeas described in connection with the embodiment o'r' our invention shownin Fig. G. Under normal conditions, the parts are in position as shownin Fig. ll, the potential winding ll. being connected across conductorsl, Assu ling a fault between conductors l and Q, such that al reversalot' power taires place then since the potentials 1, 3 and 2, 3 do notdecrease sufciently to cause the relays Q2 and 23 to drop out thepotential winding` 1l would remain energized by the potential mostaffected by the fault which is not desirable in the case et a powerdirectional relay. Therefore, in the circuit of one or" th relays 22, 23contacts 33 are arrange; to bc controllerby an rincer-voltage relay Selihaving its winding connected acres',4 conductors l, 2. Consequently,upon the tall.

in potentie-.l across these conductors, the relay 3st drops out andopens the cirnit et relay 22. This relay being thus deenergized dropsout and permits the movable Contact 2T under the bias ot' springl toengage the tired contact 26. ln this way the potential winding ll isconi'rected across the conductors 3 and is, therefore, cnergized by apotential leastattracted by the ilanlt. Assuming a 'fault betweencfnidnc tors l, l, the relay will drop out because ot the tall inpotential across the condnctors l., 8 and the potential winding ll willbe connected across the conductors f3, El. Similarly, tor a faultbetween conductors 5, the potential winding will be connected acrossconductors l, 3. Thus, in each case the potential winding ll isconnectel to be energized in accordance with a potential other than thatbetween the tau ty conductors so that in conjunction with thecoonerating current winding l0 a strong oper-zit ing torce is assured. Y

In Figs. l, G, Yl0 and ll, it is obvious that only one ot the relays 7is employed and that this relay insures protection 'for faults betweenphases and faults to ground unless the latter occur on conductor 2l. Thenumber ot relatively expensive relays is, theretore, reduced to aminimum while the over-- current relays le and l5 or the underwolt agerelays 22, 23 and 34: employed are rela-- tively inexpensive.

Vhile we have shown and described several embodiments ot our invent-ion,ne do not desire to be limited to the exact ai rangements shown and desc-bed but to cover in the appended claims all those modifications thattall within the true spit-'zt and scope et om' invention.

Trl hat we claim as new and. desire to cure o v Leiters Patent oi theUnited States. is

l. A protective system tor an electric circuit comprising a relay havinga current winding and a potentil win'tling, and relay means operative inresponse to an abnormal condition on said circuit selectively to etectthe energization of said potential winding in accordance with thepotential difference between two ot the conductors ot said circuit.

2. In a protective system tor a polyphase circuit, a relay comprising acurrent winding and a potential winding, means tor controlling theenergization ot said current winding in accordance with the current in afaulty conductor of said circuit, and means responsive to the electricalcondition ot said circuit tor selectively connecting said por St) lit)tential winding ter energi'zation in accordance with the potential otany phase of said circuit dependent upon the phase at fault.

A protective system tor an electric circuit comprising a relay having acurrent winding` connected to loe energized in accordance with thedifference between the currents in two of the conductors ot said circuitand a potential winding, and relay ineens operative in respon/se to anabnorinal condition on said circuit selectively to etitect theenergization ot' said potential windinfcT in accordance with thepotential diftercnce between two et the conductors oi said circuit.

r-r protect-ive svstein for an alternating electric current circuitcomprising` a relay raving a cuirent winningl connected to be uiergizedin accordance with the dill'erence oetwecn the lcurrents in two oi theconduc tors et said circuit and a normally deener- @ized potentialvinding, and relay nieans operative in response to an abnorinalcondition on said circuit selectively to etfect the energization ot saidpotential winding` in accordance with the potential difference betweentwo oit' the conductors ot said circuit.

il protective system for a polyphase circuit coinl'irising a relayhaving a current windine connected in series relation with said circuitand a potential winding, and a plurality of oven/current rela'ysconnected to be energized respectively in accordance with the currentsin the conductors ot said circuit and operative in response to a faultbetween phases on said circuit selectively to connect said potentialwinding for energizeticn in accordance with the potential of any phaseci said circuit dependent upon the phase at `fault.

A protective system for a polyphase circuit coinprisin;l a relay having'a current windir connected to be energized in accordance with thedifference between the currents in two ot 'the conductors ot saidcircuit and a potential wiltr ing7 and a plurality of relays connectedto be energized respectively in accordance with the currents in said twoconductors and operative in response to a fault between any two ot' theconductors of said circuit selectively to etlect the energization oitsaid potential winding in accordance with the potential ditl'ereucebetween the taulty conductors.

tential diii'crence between the faulty con- /lw-f 1 une ois.

l protective systeni for a polyphase electric circuit cocipriaingl arelay having cooperating current and potential windings7 and ineensoperative in response to an abnormal condition on said circuitselectively to connect said potential winding for cnergization inaccordance with the potential nicst ai'lected by the abnorinalcondition.

9. A protective systcin for an electric circt 't coinprising` a relayhavingl cooperating current and potential windings, and a plurality oimerciurent relays connected to be cnere'ized resiectively iu accordancewith the currents in a 1plurality ol the conductors of said circuitoperative ,in response toA current above a predetermined valueselectively to connect said potential winding for energization inaccordance with the potential inost affected hy a fault.

lO. n. protective system Ytor a polyphase alternating` current circuitcomprising a relay having a current winding' connected to be energizedin accordance with the ditterence between the currents in two ot theconductors of the circuit and a cooperating' potential .viuding7 and aplurality oit relays connected to be energized reslicctively in:wcordauce with the currents in said two coiiductors and operativ inrcsponse to a tault between any two ot the conductors ot the circuitselectively to connect said potential winding' 'for erergization inaccordance with the potential ot the circuit sul stantially in phasewith the current in said current winding.

ln witness whereof, we have hereunto set our hands this lst day ofOctober 192i,

JOSEF BERMANNS. OTTO MAYR.

